Formation-sampling apparatus



March 4, 1969 E. F. BRIEGER FORMATION-SAMPLING APPARATUS I of 2 Sheet Filed June 29, 1967 77707 e 2 ff .49//e e/ INVENTOR.

,qrra gg March 4, 1969 E. F. BRIEGER FORMATION-SAMPLING APPARATUS Sheet Filed June 29, 1967 5/22/27 2 f. fi/ve e/ INVEN'IOR.

United States Patent 3,430,714 FORMATION-SAMPLING APPARATUS Emmet F. Brieger, Needville, Tex., assignor to Schlumberger Technology Corporation, Houston, Tex., a corporation of Texas Filed June 29, 1967, Ser. No. 649,952 US. Cl. 175-78 12 Claims Int. Cl. E21b 49/02; B28d 1/04 ABSTRACT OF THE DISCLOSURE The particular embodiments described herein as illustrative of two forms of the invention are directed to borehole apparatus for obtaining and collecting a plurality of elongated samples from earth formations traversed by the borehole. To accomplish this, the disclosed tool includes particularly-arranged cutting wheels that are extended to make cuts along the face of an adjacent formation as a carrier supporting the wheels is moved longitudinally. By virtue of the arrangement of the cutting wheels, an elongated formation sample is completely cut out of the earth formation being sampled.

Accordingly, as will subsequently become more apparent, the present invention pertains to new and improved earth formation sample-taking apparatus; and, more particularly, this invention relates to means for cutting away continuous samples of earth formations along a substantial interval of the wall of a previously drilled borehole.

Heretofore, formation samples have usually been obtained from previously drilled boreholes by explosively propelling into the adjacent wall of a borehole one or more tubular bodies or so-called bullets having appropriately arranged forward cutting edges. As these bullets penetrate the borehole wall, a generally cylindrical core of the formation material is driven into each bullet so that, when the bullets are subsequently retrieved, the cores in each will be recovered at the surface for examination. Typical of such core-taking bullets are those shown in Patents Nos. 2,678,804, 2,923,530, 3,072,202 and 3,220,490.

It is recognized, of course, that although such coretaking bullets have been highly successful, the most ideal arrangement would be to obtain a continuous sample of an earth formation from along a substantial vertical interval of a borehole. Heretofore, this has not been commercially feasible at least from boreholes that have been previously drilled.

One tool as shown in Patent No. 3,173,500 has been proposed, however, in which a pair of rotatable outwardlyconver-ging cutting wheels are cooperatively arranged to be extended outwardly to cut their way into an adjacent formation. Then, as they are slowly raised, the cutting wheels will cut an elongated wedge-shaped formation sample out of the borehole wall. This sample is caught by the tool and returned to the surface.

The cutting wheels used in that tool are typical cutting wheels with diamonds embedded around their circumference and in a number of radial paths along their outer faces. The cutting wheels are so arranged that their outermost peripheral edges all but touch. Thus, as they cut out a formation sample, these wheels cannot completely cut away the sample but will instead leave a thin vertical web along the longitudinal apex of the prismatic sample holding it to the formation. It will be appreciated, of course, that as the cutting wheels wear, this web will become somewhat thicker. Thus, it is not at all unlikely that in particularly hard formations, a formation sample could be retained in place by such a web even though most of the sample had been cut away.

Accordingly, it is an object of the present invention to provide new and improved cutting means for fully cutting away elongated samples from earth formations.

This and other objects of the present invention are obtained by mounting a pair of converging cutting wheels so that the peripheral edge of one wheel approaches contact with a point on the adjacent side of the other wheel that is spaced radially inwardly from the periphery of the other wheel. Thus, as the wheels are moved in unison along an earth formation, the above-mentioned other wheel will be cutting somewhat deeper into the formation than the first-mentioned wheel so as to cut away any web that would otherwise be left.

The novel features of the present invention are set forth with particularity in the appended claims. The operation together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings, in which:

FIGURE 1 depicts a core-slicing tool with cutting wheels arranged in accordance with the present invention in a borehole and in position to obtain an elongated sample;

FIGURE 2 is a schematic representation of the intermediate portion of the tool shown in FIGURE 1;

FIGURE 3 is a schematic representation of a groove system that may be employed with the tool shown in FIGURES 1 and 2;

FIGURE 4 is a partial cross-sectional view taken along the lines 44 in FIGURE 3;

FIGURE 5 is a cross-sectional view of the core-slicing tool shown in FIGURES 1 and 2 and showing a preferred manner of arranging its cutting wheels in accordance With the present invention; and

FIGURE 6 is a partial view of an alternate arrangement of the present invention.

Turning now to FIGURE 1, a core-slicing tool 10 arranged for use with the present invention is shown suspended from a cable 11 in a borehole 12 and in position for cutting means such as a pair of similar cutting wheels 13 and 14 to cut away an elongated prismatic or wedge-shaped sample 15 from the adjacent wall of an earth formation 16. As seen in FIGURE 1, the tool 10 is preferably comprised of a number of tandemly connected housings 1721 suitably arranged for enclosing the various components of the tool.

It will be appreciated, of course, that although the present invention is directed to various arrangements of the cutting Wheels 13 and 14, the general arrangement and operation of the tool 10 as a whole should be first described. Although the following description is believed to be sufiicient, copending applications Serial Nos. 649,- 929 and 649,976 filed simultaneously herewith more fully describe those other portions of the tool 10.

The upper housing 17 preferably encloses suitable circuitry for locating the tool 10 at a desired position in the borehole 12 as well as for controlling the various components in the tool and transmitting information and power through the various conductors in the suspension cable 11. Hereagain, the circuitry preferably employed with the cutting means of the present invention is fully described in a copending application Ser. No. 649,976 filed simultaneously herewith.

The next lower housing 18 preferably includes suitable longitudinally spaced, hydraulically actuated pistons 22 for selectively extending a wall-engaging member 23 on the rear of the tool 10 laterally against one side of the borehole 12 to shift the forward face of the core-slicing tool in the opposite direction. To make the wall-engaging member 23 selectively operable from the surface, a hydraulic pump 24 and chamber 25 (shown in dashed lines) are arranged to extend and retract the wall-engaging member by pumping hydraulic fluid into the piston chambers either behind or ahead of the pistons 22. By maintaining an increased hydraulic pressure behind the pistons 22, the wall-engaging member 23 will, of course, urge the forward face of the tool 10 against the opposite wall of the borehole 12 with a corresponding force.

The intermediate housing 19 of the tool 10 supports the cutting wheels 13 and 14 that, in accordance with the present invention, are respectively mounted in converging vertical planes and arranged to rotate about independent, outwardly diverging axes themselves lying generally in the same horizontal plane and intersecting each other at a suitable angle. A longitudinal opening 26 is provided along the forward wall of the housing 19 diametrically opposite from the wall-engaging member 23. As will subsequently be explained in greater detail with respect to FIGURES and 6, the cutting wheels 13 and 14 are suitable arranged and sized in relation to one another so that, when extended, their peripheral edges will pass through the housing opening 26 and all but come together at about the point of intersection of the three aforementioned planes. Thus, by moving the wheels 13 and 14 in unison in a generally vertical direction, the generally wedged-shaped or triangular prismatic sample 15 will be cut from the adjacent formation 16.

To gain entrance for the cutting wheels 13 and 14 into the formation 16, means (to be subsequently described) are provided for advancing the wheels outwardly and upwardly through the housing opening 26 to their outermost lateral position. Then, after a longitudinal cut of a predetermined length has been made, the cutting wheels 13 and 14 are returned along an upwardly inclined path and back through the housing opening 26 until they are fully retracted. The cutting wheels 13 and 14 then return to their original starting position while still fully retracted.

The lower housing 21 of the tool is arranged to receive a plurality of core samples and keep them segregated from one another. Generally speaking, the housing 21 is arranged in such a manner that a plurality of compartments therein (not shown will be sequentially positioned to each successively receive a formation sample, as at 15, as the tool 10 is operated. In this manner, the tool 10 can be employed on a single trip in the bore 12 to recover a large number of formation samples that will be separately disposed in the compartments in a predetermined order.

Turning now to FIGURE 2, a schematic representation is shown of the intermediate housing 19 of the tool 10 in which the cutting wheels 13 and 14 are confined. In general, the cutting wheels 13 and 14 are operatively mounted below an enclosed housing or enclosure 27 that is, in turn, secured to two parallel tubular members 28 (both seen in FIGURE 5). These tubular members 28 are each slidably disposed about substantially longer, paralled longitudinally rods 29 (both seen in FIGURE 5) that are secured only at their upper and lower ends to the tool housing 19 and spaced away from the rear wall thereof. The opposite ends of these tubular members 28 are slidably sealed around the elongated rods 29. A piston member 30 (only one shown in FIGURE 2) is fixed at an intermediate position on each of the elongated rods 29 and slidably sealed relative to the internal bore of its associated tubular member 28 to define therein separate upper and lower fluid-tight chambers 31a and 31b.

Accordingly, it will be appreciated that by developing a higher fluid pressure in the upper hydraulic chambers 31a than that in the lower hydraulic chambers 31b the tubular members 28 and enclosure 27 secured thereto will be moved upwardly along the elongated rods 29 relative to the tool housing 19. Similarly, by imposing a higher pressure in the lower hydraulic chambers 31b than that in the upper hydraulic chambers 3111, the enclosure 27 will travel downwardly along the rods 29.

To develop such higher pressures in the chambers 31a and 31b, a suitable hydraulic pump 32 is mounted within the enclosure 27. Fluid lines 33a and 33b are respectively connected between the hydraulic chambers 31a and 31b and the pump 32. By selecting a motor-driven pump 32 and filling the chambers 31a and 31b with a suitable hydraulic fluid, the pump can be selectively operated from the surface to transfer fluid between the hydraulic chambers to accomplish the desired travel of the enclosure 27 along the elongated rods 29.

By arranging a typical bellows or piston (neither shown) at a convenient point in a wall of the enclosure 27, the hydraulic fluid in the enclosure and chambers 31a and 31b will be maintained at a pressure at least equal to the hydrostatic pressure of fluids or so-called mud in the borehole 12. In this manner, by pressurebalancing the hydraulic system relative to the borehole hydrostatic pressure, the hydraulic pump 32 needs only to develop a pressure suflicient to overcome the weight of the enclosure and whatever friction that may be encountered in moving the cutting wheels 13 and 14 and the enclosure 27.

To power the cutting wheels 13 and 14 of the present invention, a prime mover, preferably an electric motor 34, is also fitted into the enclosure 27 and its shaft 35 connected to the cutting wheels by suitable power-transmission means, such as a universal joint 36 which is connected by way of another shaft 37 to a right-angle gear drive 38 having outwardly diverging wheel shafts 39 and 40 at an angle to one another. By locating the cutting wheel motor 34 in the enclosure 27, it will also be pressure balanced in the same manner as the motor for the pump 32. Similarly, as best seen in FIGURE 5, by enclosing the shafts 35 and 37 and universal joint 36 in an oil-filled tube 41 that is fluidly sealed at its opposite ends to the enclosure 27 and gear drive 38 and in fluid communication with each, the power-transmission means will also be completely pressure-balanced.

A pair of depending arms 42 disposed on opposite sides of the protective tube 41 are connected at their lower ends to the gear drive 38 and pivotally connected at their upper ends to the enclosure 27 so as to pivot about an axis lying generally in the same horizontal plane as the pivotal axis of the universal joint 36. Outwardlybiased pins 43 (both seen in FIGURE 5) near the free ends of the pivoted arms 42 are slidably disposed in a labyrinth-like system of grooves 44 (only one system seen in FIGURE 2) formed in the interior side walls of the intermediate housing 19 on opposite sides of the longitudinal opening 26 therein. As will subsequently become apparent, these groove systems 44 are so arranged that upward longitudinal travel of the enclosure 27 from its full-line position to its dashed-line position shown in FIGURE 2 will be effective (through the coaction of the guides 43 in their respective groove system) to direct the cutting wheels 13 and 14 along the path A-B-C-D depicted in FIGURE 2. Then, upon downward travel of the enclosure 27 back to its full-line position shown in FIG- URE 2, the groove systems 44 and guides 43 will direct the cutting wheels 13 and 14 along the path D-A toward their initial position.

As seen in FIGURE 3, the groove systems 44 are each arranged in a closed loop having two parallel longitudinal portions 45 and 46 of unequal length and spaced apart from one another. The shorter grooves 46 are connected at their opposite ends to the longer grooves 45 by oppositely-directed inclined grooves 47 and 48 which respectively intersect the longer grooves at longitudinally spaced intermediate points.

Accordingly, as the cutting wheels 13 and 14 move along the path A-B, they will be moving upwardly and outwardly as they cut their way into the formation 16. Then, as the cutting wheels 13 and 14 move upwardly from their position at B to their position at C, they will be cutting along a straight path of a length determined by the vertical height of the shorter grooves 46. Upon reaching their position at C, the cutting wheels 13 and 14 will be retracted as they move further upwardly and cut their way toward their position at D. Thus, once the cutting wheels 13 and 14 have reached the position at D, a prismatic sample, as at 15, with tapered ends will have been cut out of the formation 16 and dropped into the core-receiving housing 21 therebelow.

The groove systems 44 must, of course, be arranged to insure that the guide pins 43 are diverted into the lower inclined grooves 47 as the enclosure 27 moves upwardly. Similarly, when the enclosure 27 has reached it uppermost position (as shown in dashed lines in FIGURE 2), it is necessary that the guide pins 43 be prevented from reentering the upper grooves 48 so that the cutting wheels 13 and 14 can proceed from their position at D and directly back to their initial position at A.

Accordingly, means are provided to direct the guide pins 43 in a predetermined direction around the circuitous groove systems 44 but prevent these pins from moving in the opposite direction. As seen in FIGURES 3 and 4, an abutment 49 is provided in the lower end of each of the longer grooves 45 for preventing the guide pins 43 from entering the longer grooves as they move upwardly. To facilitate the passage of the guide pins 43, the faces of the abutments 49 are extended along the line of the downwardly facing wall of the lower inclined grooves 47 as shown in FIGURE 3. Similarly, to insure that the guide pins 43 will not re-enter the upper end of the upper inclined grooves 48 as the enclosure 27 is returned downwardly, an abutment 50 (similar to those at 49) is located across the enarance to the upper end of each of the upper inclined grooves 48. Here again, to facilitate the passage of the guide pins 43, the faces of the abutments 50 are made as a continuation of the right-hand (as viewed in FIGURE 3) side walls of the longer grooves 45. The height of each abutment, as at 49, is made less than the total depth of its associated groove 45 and an inclined ramp or surface, as at 51 (FIGURE 4), is provided from the bottom of the groove 45 up to the upper surface of the abutment, with this inclined surface rising in the direction from which the guide pin 43 is intended to be coming in that groove. Thus, as the spring-biased guide pins 43 approach their positions, at E (FIGURE 3) for example, they can retract sufliciently to move up the inclined surfaces 51 of the abutments 49 as the enclosure 27 is moved downwardly. Once the guides 43 reach the abrupt faces of the abutments, the springs 52 (FIGURE 5) will urge them outwardly to return them to their normal extended position. The inclined surfaces 53 (FIG- URE 3) on the lower ends of the upper abutments 50 in the grooves 48 will, of course, function in the same manner.

It will be noted in FIGURE 2 that the upper ends of the longer grooves 45 extend a considerable distance above the junction of these grooves with the upper inclined grooves 48. Although this extension of the longer grooves 45 is not required to guide the movements of the cutting wheels 13 and 14, the enclosure 27 itself is further stabilized by providing longitudinally spaced lateral guides (not shown) thereon adapted to remain at all times in these longer longitudinal grooves. These guides are always above the abutments 49 in the longer grooves 45 and will not, therefore, be prevented from moving upwardly or downwardly in the grooves.

Motion-translating means (not shown) are arranged in the housing 20 coupled immediately below the intermediate tool housing 19 for rotating the several compartments of the sample receiver in the housing 21 therebelow sequentially into position to receive successive formation samples, as at 15, as they are freed by the cutting wheels 13 and 14 and to segregate these samples from one another. Since a complete description of this sample receiver is not essential to a full understanding of the present invention, sufiice it to say that these samplereceiving compartments are basically comprised of a plurality of upright tubes (not shown) that are equally spaced about an axial shaft (not shown) journalled at its opposite ends in the housing 2, with these tubes being adapted to be successively rotated about the longitudinal axis of the housing into position to receive one of the formation samples 15. The upper ends of these tubes are, of course, open and their lower ends are closed. The motion-translating means in the housing 20 are arranged to rotate the sample-receiving tubes into their respective positions in response to the longitudinal travel of the enclosure 27. For further details, complete descriptions of the motion-translating means in the housing 20 and the sample receiver in the housing 21 are found in the aforementioned copending application Ser. No. 649,976 filed simultaneously herewith.

Turning now to FIGURE 5, the cutting wheels 13 and 14 are shown as they are preferably arranged in accordance with the present invention. The cutting wheels 13 and 14 are typical, preferably with diamonds being embedded around their circumference and along radial paths on their external surfaces. Of particular significance, it will be noted that the outer edges of the cutting wheels 13 and 14 do not converge together at a common point. Instead, as shown in FIGURE 5, one of the wheels 13 is slightly smaller in diameter than the other wheel 14. Thus, by mounting the cutting wheels on a gear drive 38 with symmetrically arranged shafts 39 and 40, the smaller wheel 13 will approach an intersection with the adjacent side of the larger wheel 14 at a point thereon that is radially displaced from its periphery. It should be further noted that the side of the larger wheel 14 nearest the smaller wheel 13 is recessed at least near its outer edge, as at 54, so as to leave a laterally directed peripheral rim or lip, as at 55, on the larger wheel. Thus, by arranging the cutting wheels 13 and 14 as shown in FIGURE 5 with the peripheral lip 55 of the larger wheel extending forwardly of and at least partially overlapping the periphery of the smaller wheel, it will be appreciated that the resulting kerf of the larger wheel will overlap that of the smaller wheel so as to cut away any vertical web that would otherwise remain to join the longitudinal apex of a formation sample 15 to the formation 16. Moreover, as the cutting wheels 13 and 14 wear, this web will continue to be completely cut away until the converging edges of the wheels are separated from one another a considerable distance.

Turning now to FIGURE 6, an alternate arrangement is shown of cutting wheels 13' and 14 in accordance with the present invention. In general, the difference between the arrangement shown in FIGURES 5 and 6' is that in FIGURE 6 the larger wheel 14' is not recessed. Thus, the smaller wheel 13' merely approaches an intersection with a radially displaced point on the larger wheel 14' and a thin web would theoretically be left between the resulting kerfs as a sample is cut from a formation. It will be appreciated, however, that since the cutting wheels 13' and 14' will usually not leave perfectly complementary kerfs, the attendant crumbling, be it ever so slight, will leave little or no web which might otherwise prevent the sample 15 from being freed from the formation 16.

It will, of course, be realized that the same results as described with reference to either FIGURE 5 or FIG- URE 6 can be obtained with cutting wheels (not shown) of the same diameter. By mounting one of these wheels on an axis displaced slightly to the rear of the axis for the other wheel, equal-diameter cutting wheels can be otherwise arranged in the same manner as those shown in either FIGURE 5 or FIGURE 6.

Accordingly, it will be appreciated that the present invention insures that a formation sample is fully cut away as a core-slicing tool, such as at 10, is operated. By arranging converging cutting wheels as shown in FIG- URE 5 with one wheel having an enlarged portion ahead of and at least partially overlapping the periphery of the other wheel, the resulting kerfs produced in an earth formation as the wheels are operated will at least coincide so as to fully cut away any web that might otherwise be left to interconnect a formation sample to the formation. Similarly, by arranging converging cutting wheels as shown in FIGURE 6, the resulting kerfs will be sufficiently close to one another that at least the adjacent walls of the kerfs at their nearest point will be crumbled to reduce or fully remove any intervening web and free the sample from the earth formation.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects; and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. Apparatus for obtaining samples of earth formations traversed by a borehole comprising: a support adapted for suspension in a borehole; and formation-sampling means on said support and adapted for travel relative thereto, said formation-sampling means including first and second cutting wheels respectively arranged in converging planes having an intersection to one side of said support, with the peripheral edge of said first cutting wheel approaching contact with a point on the adjacent side of said second cutting wheel that is spaced radially inwardly from the peripheral edge of said second cutting wheel.

2. The apparatus of claim 1 wherein said adjacent side of said second cutting wheel is recessed to at least partially receive said peripheral edge of said first cutting wheel.

3. The apparatus of claim 1 wherein said second cutting wheel has an enlarged peripheral cutting edge projecting toward and overlapping said peripheral edge of said first cutting wheel.

4. The apparatus of claim 3 wherein said adjacent side of said second cutting wheel is recessed to at least partially receive said peripheral edge of said first cutting wheel.

5. Apparatus for obtaining samples of earth formations comprising: a support adapted for suspension in a borehole; formation-sampling means on said support and adapted for longitudinal travel relative thereto, said formation-sampling means including first and second cutting wheels respectively arranged in converging vertical planes having an intersection to one side of said support, with the peripheral edge of said first cutting wheel approaching contact with a point on the adjacent side of said second cutting wheel that is spaced radially inwardly from the peripheral edge of said second wheel; and means selectively operable from the surface for moving said cutting wheels laterally to bring said peripheral edges into contact with an earth formation.

6. The apparatus of claim 5 further including means for collecting formation samples cut out of an earth formation by said cutting wheels.

7. The apparatus of claim 5 wherein said adjacent side of said second cutting wheel is recessed to at least partially receive said peripheral edge of said first cutting wheel.

8. The apparatus of claim 5 wherein said second cutting wheel has an enlarged peripheral cutting edge projecting toward and overlapping said peripheral edge of said first cutting wheel.

9. The apparatus of claim 8 wherein said adjacent side of said second cutting wheel is recessed to at least partially receive said peripheral edge of said first cutting wheel.

10. Apparatus for obtaining samples of earth formations comprising: a support adapted for suspension in a borehole; and formation-sampling means on said support adapted for longitudinal travel relative thereto and including driving means having first and second rotatable shafts arranged in a common plane and respectively aligned along outwardly-diverging first and second axes in said common plane, and first and second cutting wheels operatively mounted on said first and second shafts, respectively, for rotation thereby in converging planes intersecting said common plane and one another, with the peripheral edge of said first cutting wheel approaching contact with a point on the adjacent side of said second cutting wheel that is spaced radially inwardly from the peripheral edge of said second cutting wheel.

11. The cutting apparatus of claim 10 wherein said adjacent side of said second cutting wheel is recessed to at least partially receive said peripheral edge of said first cutting wheel.

12. The cutting apparatus of claim 10 wherein said second cutting wheel has an enlarged peripheral cutting edge projecting toward and overlapping said peripheral edge of said first cutting wheel.

References Cited UNITED STATES PATENTS 2,540,793 2/1951 Metzger 15 2,978,847 4/1961 Shoenmakers 125-15 X 3,173,500 3/1965 Stuart -78 X 3,371,452 3/1968 Mabey 125--15 X DAVID H. BROWN, Primary Examiner.

US. Cl. X.R. 125-15 

